Biosynthesis of gold nanoparticles using a freshwater green alga, Prasiola crispa

•Gold nanoparticles were biosynthesized using a fresh water green alga, Prasiola crispa.•Powder XRD showed a face-centered cubic structure of gold having average crystallite size 9.8 nm.•The TEM images revealed the material to be nearly spherical in shape with sizes 5–25 nm.•The current strategy is facile, one step, and eco-friendly.

Biosynthesis of gold nanoparticles has been achieved via reduction of an aqueous chloroauric acid solution with dried biomass of a freshwater epilithic green alga, Prasiola crispa, collected from a high altitude river ecosystem in Arunachal Pradesh state, India. The synthesized nanoparticles were characterized by UV–visible, powder X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, and DLS studies. The UV–visible spectrum of the synthesized gold nanoparticles showed a surface plasmon resonance (SPR) around 535 nm after 12 h. The powder XRD pattern furnished evidence for the formation of face-centered cubic structure of gold having average crystallite size 9.8 nm. The TEM images showed the nanoparticles to be nearly spherical in shape with sizes in the range of 5–25 nm.